Tension device for saws



(No Model.) 3 Sheets-Sheet 1.

S.J.-LE0NARD. TENSION DEYICE-POR SAWS, 650.

No. 547,792.` Patented ont. z15, 1895.

2. t e e h S e e h S kun D R A N O un L .JH S. d. d 0 M 0 W TENSION DEVICE FOB. SAWS, Buc.

wh/Lewes qxl/@Awww (N Model.) 1 I I 3 Sheets-Shet' S. J. LEONARD. V

TENSION DEVISE` FOR SAWS, &0.

No. 547 92. Patented Oct'. 15,1895.

.mmwwlmlllli Illy i MMMMIHIIIIIIHIIIIIIIIIIIIII!"UM iiilllllll I] i Q/ihfreoocd FFICEO A'rnNT SUMNER J. LEONARD, OF MONTGOMERY, PENNSYLVANIA.

TENSION DEVICE FOR SAWS, C.

SPECIFICATION forming part of Letters Patent No. 547,792, dated October 15, 1895.

Application filed July 16, 1895. Serial No. 556,174. (No model.)

To all whom it may concern.-

Be it known that I, SUMNER J. LEONARD, a citizen of the United States, residing at Montgomery, in the county of Lycoming and State of Pennsylvania, have invented certain new and useful Improvements in Tension Devices for Saws, o., of which the following is a specilication.

My invention relates to sawing-machines, and has reference more particularly to that olassof machines in which avertically-reciprocating saw is employed.

The object of the invention is to equalize the strain on the saw at all points and in all positions. In the preferred construction I employ two arms or levers and corresponding torsion-springs, with intermediate bearings, and so arrange the parts that by increasing the leverage as the strain on thespring increases and decreasing the leverage as the strain on the spring decreases the saw strain will be equalized.

In the drawings, which show the preferred embodiment of the invention, Figure 1 is a front face view of a portion of a machine with my improvements applied; Fig. 2,a face view, partly in section, of a portion of the upper part of the machine, showing the levers and attendant parts; Fig. 3, a plan view of one of thelevers,springs, housings, dac.; Fig. 4, a side or end view of the same, and Fig. 5 a perspective view of the spring and attendant parts separated.V l

A indicates a portion of the frame of the sawing-machine, B B the reciprocating blocks or holders to which the saw C is attached, and D the pitman for imparting motion to the saw, all of which parts are or may be of the usual construction.

The frameA is provided at or near its upper end with a cross-bar E, from the rear side of which project the arms F F, which arms, as shown in Figs. 2, 3, and 4, are preferably semicircular throughout the greater part of their length and then terminate in the hollow hubs G. Fitting into each hub is a cylindrical block I-I, which is grooved circumferentially, as at ci, to receive a set-screw b, by means of which the block is held in place, and which block is further provided with a lug or ear c, projecting up through a slot or opening in the hub. An adjusting-screw I, carried by alugor extension J on the hub, is designed tobear upon or against the lug or ear c of the block, and thereby eect a rotary adjustment of the latter. Block H is further provided with a socket to receive one end of an L-shaped torsion-spring K, the torsional member d. Vof which is seated loosely in the hollow or open arm F, while the lever end or part e extends parallel with and in rear of the cross-bar E. At the end of part or arm e of the spring is a bearing foot or platef, which has a socket to receive the pointed or knife-edged bearingblock g, secured to the under side of a lever L near its outer end, as shown in Figs. land 2. Lever L is connected at its inner end by means of a strap M with the upper sawholder B and is provided on its upper face, near its outer end, with a socketed bearingplate h to receive the pointed screw z', carried atthe upper end of the yokeN. This yoke N is in turn provided at its lower end with a socket-ed bearing-plate j to receive the end of the pointed bearing-screwlc, carried at the end of cross bar E, as shown in Figs. 1, 2, and 4. I desire to state here that there are two levers and springs'and attendant parts; but as they are similar only one set has been specifically described, and, further, while these levers move up and down in unison, both being attaehed to the strap M, I have, in Fig. 2, shown one of them raised and the other lowered, in order to illustrate the position the parts assume when the lever is moved toits different positions. When the lever is raised, as at the right-hand end of Fig. 2, the spring isrelieved of .tension or torsional strain, and the pivots or bearing-point f g, h i, andy' lc are at the farthest distances apart. Vhen, however, the saw descends and the lever is carried down, as at the left-hand end of Fig. 2, the

the arm or member e tends to twist the torsional member d. It will be noted that when IOO the resistance the upper or yoke-and-lever bearing h t' moves inward or over toward the end of the spring-arm e. From this it willbe seen that the fulcrum h1' for the lever L will be shifted automatically and in proportion to the movement of the point of contact of the springarm e with the lever, the fulcrum moving inward as the arm is carried down by the lever and moving outward as the arm rises. By turning the screw I the tension of the spring may be varied, as required.

Vhile I have shown two sets of levers and springs, I do not wish to be understood as being confined to such arrangement, one spring and lever being obviously capable of accomplishing the saine result.

The invention is obviously applicable to other devices than sawmills-iu fact, to any reciprocating device upon which it is desired to exert a constant pull or strain.

Ilaviug thus described my invention, what I claim is l. In combination with a main frame and a saw; a lever; a connection between the inner end of the lever and the saw; a spring carried by the main frame and provided with a vertically-movable arm for supporting the 1ever at a point between the ends of the latter; and a yoke pivotally connected at its lower end to the main frame and provided at its upper end with a fulcrum for the lever;

whereby the fulcrurn of the lever will be moved inward as the spring is put under tension by the lever and the point of contact of the lever with the spring is depressed, and moved outward as the tension is decreased.

2. In combination with a frame having an arm F and hub G; a block II fitting the hub and provided with lug c and groove a; a set screw ZJ; an adjusting screw I carried by the hub to engage the lug; an L-shaped springsecured at one end to the block; and a lever acting upon the other end of the spring.

3. In combination with a main frame and a reciprocating device; a lever connected at its inner end with said device; a spring on the main frame provided with a vertically-movable arin for supporting said lever between the ends of the latter; and a yoke pivotally connected at its lower end with the main frame and provided at its upper end with a fulcrum for the lever; whereby the fulcrum ofthe lever will be shifted as the arm of the spring rises and falls according to the tension applied to the spring by the lever.

In witness whereof I hereunto set my hand in the presence of two witnesses.

SUMNER J. LEONARD. Witnesses:

E. B. KETNER, M. S. HIGH. 

